<!DOCTYPE>
<HTML>
<HEAD>
  <TITLE> 爱心 </TITLE>
  <META NAME="Generator" CONTENT="EditPlus">
  <META NAME="Author" CONTENT="">
  <META NAME="Keywords" CONTENT="">
  <META NAME="Description" CONTENT="">
  <style>
    html,
    body {
      height: 100%;
      padding: 0;
      margin: 0;
      background: #000;
    }

    canvas {
      position: absolute;
      width: 100%;
      height: 100%;
    }
  </style>
</HEAD>

<BODY>
  <canvas id="pinkboard"></canvas>
  <script>
    /*
   * Settings
   */
    var settings = {
      particles: {
        length: 500, // maximum amount of particles
        duration: 2, // particle duration in sec
        velocity: 100, // particle velocity in pixels/sec
        effect: -0.75, // play with this for a nice effect
        size: 30, // particle size in pixels
      },
    };

    /*
     * RequestAnimationFrame polyfill by Erik Möller
     */
    (function () { var b = 0; var c = ["ms", "moz", "webkit", "o"]; for (var a = 0; a < c.length && !window.requestAnimationFrame; ++a) { window.requestAnimationFrame = window[c[a] + "RequestAnimationFrame"]; window.cancelAnimationFrame = window[c[a] + "CancelAnimationFrame"] || window[c[a] + "CancelRequestAnimationFrame"] } if (!window.requestAnimationFrame) { window.requestAnimationFrame = function (h, e) { var d = new Date().getTime(); var f = Math.max(0, 16 - (d - b)); var g = window.setTimeout(function () { h(d + f) }, f); b = d + f; return g } } if (!window.cancelAnimationFrame) { window.cancelAnimationFrame = function (d) { clearTimeout(d) } } }());

    /*
     * Point class
     */
    var Point = (function () {
      function Point(x, y) {
        this.x = (typeof x !== 'undefined') ? x : 0;
        this.y = (typeof y !== 'undefined') ? y : 0;
      }
      Point.prototype.clone = function () {
        return new Point(this.x, this.y);
      };
      Point.prototype.length = function (length) {
        if (typeof length == 'undefined')
          return Math.sqrt(this.x * this.x + this.y * this.y);
        this.normalize();
        this.x *= length;
        this.y *= length;
        return this;
      };
      Point.prototype.normalize = function () {
        var length = this.length();
        this.x /= length;
        this.y /= length;
        return this;
      };
      return Point;
    })();

    /*
     * Particle class
     */
    var Particle = (function () {
      function Particle() {
        this.position = new Point();
        this.velocity = new Point();
        this.acceleration = new Point();
        this.age = 0;
      }
      Particle.prototype.initialize = function (x, y, dx, dy) {
        this.position.x = x;
        this.position.y = y;
        this.velocity.x = dx;
        this.velocity.y = dy;
        this.acceleration.x = dx * settings.particles.effect;
        this.acceleration.y = dy * settings.particles.effect;
        this.age = 0;
      };
      Particle.prototype.update = function (deltaTime) {
        this.position.x += this.velocity.x * deltaTime;
        this.position.y += this.velocity.y * deltaTime;
        this.velocity.x += this.acceleration.x * deltaTime;
        this.velocity.y += this.acceleration.y * deltaTime;
        this.age += deltaTime;
      };
      Particle.prototype.draw = function (context, image) {
        function ease(t) {
          return (--t) * t * t + 1;
        }
        var size = image.width * ease(this.age / settings.particles.duration);
        context.globalAlpha = 1 - this.age / settings.particles.duration;
        context.drawImage(image, this.position.x - size / 2, this.position.y - size / 2, size, size);
      };
      return Particle;
    })();

    /*
     * ParticlePool class
     */
    var ParticlePool = (function () {
      var particles,
        firstActive = 0,
        firstFree = 0,
        duration = settings.particles.duration;

      function ParticlePool(length) {
        // create and populate particle pool
        particles = new Array(length);
        for (var i = 0; i < particles.length; i++)
          particles[i] = new Particle();
      }
      ParticlePool.prototype.add = function (x, y, dx, dy) {
        particles[firstFree].initialize(x, y, dx, dy);

        // handle circular queue
        firstFree++;
        if (firstFree == particles.length) firstFree = 0;
        if (firstActive == firstFree) firstActive++;
        if (firstActive == particles.length) firstActive = 0;
      };
      ParticlePool.prototype.update = function (deltaTime) {
        var i;

        // update active particles
        if (firstActive < firstFree) {
          for (i = firstActive; i < firstFree; i++)
            particles[i].update(deltaTime);
        }
        if (firstFree < firstActive) {
          for (i = firstActive; i < particles.length; i++)
            particles[i].update(deltaTime);
          for (i = 0; i < firstFree; i++)
            particles[i].update(deltaTime);
        }

        // remove inactive particles
        while (particles[firstActive].age >= duration && firstActive != firstFree) {
          firstActive++;
          if (firstActive == particles.length) firstActive = 0;
        }


      };
      ParticlePool.prototype.draw = function (context, image) {
        // draw active particles
        if (firstActive < firstFree) {
          for (i = firstActive; i < firstFree; i++)
            particles[i].draw(context, image);
        }
        if (firstFree < firstActive) {
          for (i = firstActive; i < particles.length; i++)
            particles[i].draw(context, image);
          for (i = 0; i < firstFree; i++)
            particles[i].draw(context, image);
        }
      };
      return ParticlePool;
    })();

    /*
     * Putting it all together
     */
    (function (canvas) {
      var context = canvas.getContext('2d'),
        particles = new ParticlePool(settings.particles.length),
        particleRate = settings.particles.length / settings.particles.duration, // particles/sec
        time;

      // get point on heart with -PI <= t <= PI
      function pointOnHeart(t) {
        return new Point(
          160 * Math.pow(Math.sin(t), 3),
          130 * Math.cos(t) - 50 * Math.cos(2 * t) - 20 * Math.cos(3 * t) - 10 * Math.cos(4 * t) + 25
        );
      }

      // creating the particle image using a dummy canvas
      var image = (function () {
        var canvas = document.createElement('canvas'),
          context = canvas.getContext('2d');
        canvas.width = settings.particles.size;
        canvas.height = settings.particles.size;
        // helper function to create the path
        function to(t) {
          var point = pointOnHeart(t);
          point.x = settings.particles.size / 2 + point.x * settings.particles.size / 350;
          point.y = settings.particles.size / 2 - point.y * settings.particles.size / 350;
          return point;
        }
        // create the path
        context.beginPath();
        var t = -Math.PI;
        var point = to(t);
        context.moveTo(point.x, point.y);
        while (t < Math.PI) {
          t += 0.01; // baby steps!
          point = to(t);
          context.lineTo(point.x, point.y);
        }
        context.closePath();
        // create the fill
        context.fillStyle = '#ea80b0';
        context.fill();
        // create the image
        var image = new Image();
        image.src = canvas.toDataURL();
        return image;
      })();

      // render that thing!
      function render() {
        // next animation frame
        requestAnimationFrame(render);

        // update time
        var newTime = new Date().getTime() / 1000,
          deltaTime = newTime - (time || newTime);
        time = newTime;

        // clear canvas
        context.clearRect(0, 0, canvas.width, canvas.height);

        // create new particles
        var amount = particleRate * deltaTime;
        for (var i = 0; i < amount; i++) {
          var pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random());
          var dir = pos.clone().length(settings.particles.velocity);
          particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y);
        }

        // update and draw particles
        particles.update(deltaTime);
        particles.draw(context, image);
      }

      // handle (re-)sizing of the canvas
      function onResize() {
        canvas.width = canvas.clientWidth;
        canvas.height = canvas.clientHeight;
      }
      window.onresize = onResize;

      // delay rendering bootstrap
      setTimeout(function () {
        onResize();
        render();
      }, 10);
    })(document.getElementById('pinkboard'));
  </script>
</BODY>

</HTML>